Astronomy/Cosmology question

refer to first law of thermodynamics.

Haha. How about this one. If everything tends towards an increase in entropy, why did planets form? And for that matter, why does water turn into a quite ordered crystal solid we call snow?

Does this not entail that total energy in an isolated system remains the same?

Difference between a closed and open system, no?

Yes.

One can argue that the universe is a closed (isloated) system. However, to my knowledge, there isn't a way to prove this.

So i don't understand how this answers my question...

A star will emit it's energy (heat up) into surrounding matter (planets, dust, comets). Therefore, all of it's energy will be absorbed into the surrounding universe.

Heat is actually infrared light, and since light can travel in a vacuum, a star's energy can be spread very very lightly over a huge area.

one of the 3 theories of what will happen to the universe is called the big freeze. it says dark energy will win and continue to expand the universe leaving all energy scarcely spread so that everything is quivering over absolute zero

The small amount of 'order' with the forming of planets is very little compared to the entropy produced by a (distant) star going supernova, and throwing dust across the universe, having this dust captured by surrounding stars, and eventually coalescing into planets.

as for water to ice, you have to remove energy from water to make ice. the process of which you remove energy, actually increases entropy. here's a quote:

'The entropy of a system decreases only when it interacts with some other system whose entropy increases'

Self organizing principle. Look it up, I would explain it but the universe has a tendency to organization over complete chaos, hence a neatly ordered universe and systems building systems building systems (our biology). The universe is currently expanding at an accelerating rate, so eventually everything will be torn apart. We don't understand dark matter, so we can't understand what's going on with the universe's expansion. This is currently one of the biggest questions in science, and when we figure out what is responsible for this mysterious energy we will know what's going on.

Because water is a polar molecule thats how it organizes when it freezes around the nuclei. Doesnt really have anything to do with entropy. Planets form bc the bigger a meteor gets the more gravity it has to pull more matter in toward it. You are misunderstanding the law if it contradicts simple observable phenomena

"So, the 2nd law of thermodynamics means that everything tends towards high entropy. All the stars will burn out, but where does all that energy go?"

-Order and disorder have to be defined first, you could say that a soup of atoms is order, or disorder and life is order or disorder, the energy will be wasted into space, turned into entropy or mass, or arguably alter a different universe, balancing out the law of conservation of energy. 

"They burn out but the heat they emit must still be around, no? Does the radiation just dissipate into nothing?"

-It just turns into mass, unusable energy or 'disorganization' like entropy.

"What about stars that supernova? Don't they turn into nebulas, that can then re-form into stars?
Or will all the matter be inside black holes? Don't the black holes evaporate? Where does the energy go when they evaporate?"

-Remember, energy is never created nor destroyed, and we dont exactly know where the mass in a black hole goes, my theory is it becomes inaccessible through a hole in space-time, exactly like the klien bottle (http://upload.wikimedia.org/wikipedia/commons/2/21/Acme_klein_bottle.jpg)
-Now also remember that energy can be transferred into multiple types of energy, potential in the mass of objects, gravity, mass, light, heat, whatever you please, so therefore the unaccounted for energy is always there though we might not be able to trace it directly.

"Does the fact that the universe keeps expanding mean that the energy will just get so spread out that it will be stuck in the highest state of entropy? If the universe didn't expand, would the universe never die out?"

-There are many theories on this matter, such as the big tear, the big crunch etc. (look those up if you please)


"I assume this will happen, so does this mean that there will be no such thing as time when it does happen?"

-If the big tear were to happen, yes time would become useless.

"Would it then be possible for particles to spontaneously come into existence from this vacuum and create another big bang"

-Yes, if that theory is correct thats a possibility, we might never know though.

-I suggest you read Brian Green's books, The fabric of the cosmos, The hidden reality, and the elegant universe, as they would help you and you would love to read them! If you hate reading there are also DVD's on the matter and i will put links to all this stuff below for you and anyone else!

Hope this helps feel free to ask any more clarifying questions!

http://www.briangreene.org/
http://en.wikipedia.org/wiki/Brian_Greene

http://www.amazon.com/NOVA-Elegant-Universe-Michael-Duff/dp/B0000ZG0TA/ref=sr_1_4?ie=UTF8&qid=1325105248&sr=8-4

http://www.amazon.com/Hidden-Reality-Parallel-Universes-Vintage/dp/0307278123/ref=sr_1_1?ie=UTF8&qid=1325105229&sr=8-1

http://www.amazon.com/Fabric-Cosmos-Space-Texture-Reality/dp/0375727205/ref=sr_1_3?ie=UTF8&qid=1325105229&sr=8-3

http://www.amazon.com/Elegant-Universe-Superstrings-Dimensions-Ultimate/dp/0375708111/ref=sr_1_4?ie=UTF8&qid=1325105229&sr=8-4

http://www.amazon.com/Nova-Fabric-Cosmos-Brian-Greene/dp/B0056031LE/ref=sr_1_9?ie=UTF8&qid=1325105229&sr=8-9

Thanks!

In reference to the main question, yes - eventually in such a system thats allowed to run to infinity, you'd get a sort of tepid tub, where matter is distributed pretty much evenly and equally. The universe would sort of be like a thin slightly warm soup.

If you want to know about the craziest idea about the universe I've ever heard:

http://www.radiolab.org/blogs/radiolab-blog/2008/aug/12/the-multi-universes/

Go to 3:02 to skip the intro talking bit, you get a summary of what this is about. Fuck. Ing. Nuts.

Thanks for the legit response. I realize my question(s) were a bit scrambled etc.

important to keep in mind when listening to this.

IF our universe is infinite... its not possible, it DOES happen.

Crazy.

"Basically what i'm asking is that, if the universe we're to maintain the same size, would the eventual result be similar to the end of Asimov's story (a big uniform soup), or would the matter constantly re-form itself into new galaxies/stars etc.?"

-Well both notions are perfectly possible. Personally, if the universe keeps expanding and is infinate then i think it will cycle through new galaxies/stars etc forever.


"Is it correct to say that the most widely accepted one is that the universe will keep expanding forever? I recall reading about how the expansion is in fact speeding up now too..."

-Again, that is one of the most likley assumptions about our universe, but the nature of physics and astronomy is that there is always a new discovery that will change our perception once again.

-Id say that the universe's expansion is going at a rate the same as a logrithmic graph, right now it is expanding with growth expotentially, but it might reach the point of inflection and expanding with exponential decay, and we will result in a finite universe, much like a logarithmic graph of population, exponential growth > decay level out population.

-Another theory of mine about black holes [rant] is that they are portals into an inaccessible dimension that is sitting right on top of us, explaining dark energy and matter, which just rests in a different dimension right on top of us and there are infinate of these. The black holes are portals between different dimesions (universes) that act as a acme klien bottle in spacetime. A cloud of probability that can or cant happen between the dimesnions. If that made sense.